The present invention relates to a personal injector for liquid medicine. More particularly, the invention relates to a simplified injector for liquid medicine, which is intended for patients who have chronic diseases and require self-administration of liquid medicines, and which enables the user to administer a dose of liquid medicine with ease in safety as well as to perform automatic injection and control of the administration.
Conventionally, pen-type liquid drug injectors have been used for administration of liquid medicines, for example, insulin to diabetic patients. Such a drug injector generally comprises a body provided with a dosage-setting dial, an injection button, a piston and unit-setting indicator; a medicine container holder and a cap. In use, the administration of insulin is carried out by a method comprising the steps of inserting a cartridge into a medicine container holder of the body, fitting a needle on a tip of the body, injecting the liquid medicine for air-release and confirmation of fluid communication, and setting a dosage of the liquid medicine.
However, the liquid medicine injectors of the conventional pen-type have the following disadvantages: When the cartridge has been emptied, the user may have the false impression that the injector got out of order. The injection of the setting dosage can not be confirmed since the injection of the liquid medicine is carried out only while the injection button is pushed. The given dose can not be quantified accurately since the liquid medicine may drip down when the needle is accidentally taken out from the skin during administration. The correct control of administration can not be performed since the residual liquid medicine content is not expressed numerically.